Tethering pregnant female macaques allows them full movement in the cage, and clothing them with a cloth jacket protects catheter lines in both mother and fetus. Surgically implanted catheters allow researchers access to the subjects' blood system and amniotic fluid without having to stress the subjects by capture for blood draws. The catheters are used for infusing biological materials, withdrawing materials for chemical analysis, and measuring cardiovascular functioning. Although this technique has been in use for more than 10 years, the short- and long-term effects of the tethering procedure itself have not been studied. In this project we are evaluating data on maternal and fetal hormone and immune systems and autonomic nervous system activity during the last trimester of pregnancy. The primary aim is to study the postnatal growth and the neural, immune, and behavioral development of infants following prenatal tethering. A total of 12 tethered and 12 control mot her-fetus pairs will be studied over the four years needed to complete this project. The study is now in its second year. The results will document any chronic abnormalities and developmental disabilities or retardation caused by the tethering methodology and provide uninfected control data for AIDS-related maternal-fetal tethering studies. FUNDING NIH grant RR00166.